Mollusques terrestres et d'eau douce. 131 



Helix contorta Linné Syst. Nat. X (1758) p. 770; Fanna Su. éd. 2 (1761) p. 528. 



Planorbis contortus Müller Venn. Hist. II (1774) p. 162. Nilsson Hist. Moll. Su. 



(1822) p. 73. Rossmiissier Iconogr. II (18.35) p. 16. f. 117. Moquin-Tandon 



Moll. Fr. II (1855) p. 443. t. 31. f. 24—31. Jeffreys Brit. Conch. I (1862) 



p. 94. Mörch Syn. Moll. Dan. (1864) p. 52. Westerlund Sv. Moll. (1865) p. 

 103; Coll. Typ. Moll. Su. (1868) n:o 92. 



PLANOIJBIS 'DISPAR mh. 



Testa depressa, obscura, see2)e uigrescens, subtiliter arcuatim oblique 

 striatula, supra plana, centro impresso, subtus medio concava (excavatio 

 magna, irregularis, centro distincta, multo latior ac profunda); anfr. G — 7, 

 arete convoluti, tardissime accrescentes, sibi iavieem subperpendiculariter 

 adpressi, suhira profunda, canaliculata separat!; apertura rotundato-renifor- 

 rais; peristoma acutum. Diam. 4|, alt. 1^ nim. 



Plaiiorbis contortns Friele Norske Moll. (1853) p. 32. Nord, et Nyl. Fini. Moll. (1856) 

 p. 62. f. 50. 



Hab. In Suecia haic species sub formis allatis per totum regnum, 

 a maxime meridionali parte prov. Skåne saltern usque iu Luleå Lapp- 

 mark, ad. 67 — 68 lat. bor., distributa, locis plerisque (prov. Blekinge, 

 ubi rara, excepta) frequens. In Norvegia passim ad Christiania et Ber- 

 gen (Friele). FL '^ dispar pra;sertim regiones boréales habitat. 



4. Gyrauhis Agass., Hartm. Testa, saltern junior, sœpe hispida, an- 

 fiactiljus paucis, ccleriter accresceutibus, ultimo aperturam versus 

 plus minus dilatato. 



8. PLANOEBIS ALBUS Müll. 



Testa tenuis, alba, laro fusca, virescens vel cornea, subtiliter et con- 

 fertim transverse striata, semper lineis spiralibus plus minus prominentibus 

 clatlirata; anfractus ultimus aperturam versus dilatatus; apertura obliqua, ex- 

 pansa, subdeflexa. 



ami'iHeri: testa albida, pellucida, raro subfusca vel rut'escens, utrinque 

 seque umbilicata; anfr. in adultis ad siuuniuni 4, ceierrinie accrescen- 

 tes, subteretes, ultimus aperturam versus subite et forte dilatatus, re- 

 liquis omnibus major et latior, sine ullo vestigio anguli aut carence; 

 apertura rotundato-ovata; diam. 4 — 5 ram. — P. albus MÜLLER Verm. 

 Hist, n (1774) p. 164. 



jS hispidlis Drap.: testa tenuis, albescens, utrinque concaviuscula, supra 

 plana cum fossula centrali, subtus umbilicata, liueis spiralibus spiuulis 



